<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <style>
    .main {
      width: 500px;
      height: 500px;
      background-color: bisque;
    }
    .father {
      width: 400px;
      height: 400px;
      background-color: rgb(212, 124, 139);
      padding: 20px;
    }
    .son {
      width: 200px;
      height: 800px;
      background-color: skyblue;
    }
  </style>
  <body>
    <div class="main">
      <div class="father">
        <div class="son"></div>  
      </div>
    </div>
  </body>
</html>
